There are two supply destinations of coolant in a laser processing apparatus. Coolants at different temperatures are supplied to the two supply destinations, respectively. One of the supply destinations is a laser oscillator, and coolant at about 24° C. is supplied to the laser oscillator, for example. The other of the supply destinations is a laser processing machine, and coolant at 27° C. or higher that is higher than the temperature of the coolant for the laser oscillator is supplied to the laser processing machine, for example.
In a prior-art cooling system for a laser processing apparatus, two chilling machines 501 and 502 are prepared as shown in FIG. 7. The chilling machine 501 circulates coolant A (24±1° C.) to a laser oscillator 2 through a supply pipe A1 and a return pipe A2. The chilling machine 502 circulates coolant B (27° C. or higher) to a laser processing machine 3 through a supply pipe B1 and a return pipe B2.
However, a system that uses two chilling machine is less economical, because equipment cost, installation space and consumed electric power are all required for the two. A patent Document 1 listed below discloses one chilling machine that circulates coolant for two circulatory systems.
In the chilling machine disclosed in the Patent Document 1, a reheater (sub heat exchanger) is interposed between a compressor and a condenser in a refrigeration cycle, and coolant (refrigerant) whose temperature is increased by the reheater is circulated as high temperature coolant. Namely, the high temperature coolant is generated by utilizing heats of refrigerant that has absorbed exhausted heats of a supply destination of a low temperature coolant.